Many studies, mostly involving US college students, ostensibly show that young people tend to believe that more of their peers engage in heavy episodic drinking, illicit drug use and risky sex than actually do so. College students are also found to misperceive injunctive norms, thinking that their peers are more permissive of certain risk behaviours than they really are. These errors of judgement have been framed in terms of pluralistic ignorance, described as a phenomenon in which ‘a majority of group members privately reject a norm, but assume (incorrectly) that most others accept it’.